In many industrial fields, components are frequently subjected to considerable dirt accumulation and impurities that remain adhering to the surfaces of said components. However, partly due to the fact that these components are hard to reach or are used in hazardous environments, it is difficult or arduous to manually clean these components. Attempts have therefore been made to create surfaces that can feature self-cleaning effects.
In particular in the field of metrology, in which the devices used are exposed to harsh industrial conditions and are thus often covered with dirt, such dirt can significantly reduce the measuring characteristics. The term “dirt” can refer both to solid materials (such as e.g. dust) and to liquid materials, such as for example condensates. Depending on the conditions, considerable dirt accumulation can occur on the measuring device over time so that the measuring functions can be impeded or even cease altogether.
U.S. Pat. No. 6,435,025 B1 and WO 02/14804 A1 propose coatings which are based on the so-called lotus effect. In this technique the surface comprises a defined microstructure with elevations and indentations with structural dimensions ranging from 5 μm to 200 μm. The microstructure and its low-energy or hydrophobic character causes water to run off from the surface. At the same time any dirt particles located on the surface are swept away by the water that runs off.
Coatings of low-energy plastics such as for example PTFE or PVDF are a further option. As a rule such coatings are at least 1 mm thick so as to provide adequate sealing characteristics. These coatings are not transparent; as a result of their thickness they can also considerably influence the measuring characteristics of a measuring device.